Electrical connector for printed-circuit boards



E. ECCLESIA Sept. 9, 1969 ELECTRICAL CONNECTOR FOR PRINTED-CIRCUIT BOARDS 2 Sheets-Sheet l Filed Oct. 25. 1965 1N VEN TOR. EDOARDO ECCLESIA im ATTO RN S United States Patent O ELECTRICAL CONNECTOR FOR PRINTED-CIRCUIT BOARDS Edoardo Ecclesia, Ivrea, Torino, Italy, assignor to Ing. C. Olivetti & C., S.p.A., Ivrea, Italy, a corporation of Italy Filed Oct. 25, 1965, Ser. No. 505,148 Claims priority, application Italy, Oct. 30, 1964,

Int. Cl. H05k 1/12, 13/06; H01r 13/50 U.S. Cl. 339--17 Claim ABSTRACT OF THE DISCLOSURE In an electrical connector for printed-circuit boards a series of contact elements made of conductive wire are arranged in cavities of a receptacle of insulating material, said wire being bent to form two loops and its ends being firmly anchored in a point on the bottom of said receptacle so that said loops may be solidly displaced within said cavity by resilient exure around said anchorage point.

The present invention refers to an electrical connector for printed-circuit boards.

Known connectors compriseI a series of contact elements, each one arranged in a cavity of a receptacle of insulating material and each one made of an electrically conductive wire bent in such a way as to form two loops suitable for receiving a terminal therebetween.

In the known connectors the ends of said bent Wire are fixed to the receptacle at points which are close to the external borders of said cavity. Therefore said contact elements cannot substantially move from their normal operative position in the receptacle when there is misalignment between the axes of said contact elements and the axes of said terminals. Consequently, these connectors do not readily permit the insertion of plug contacts carried by printed-circuit boards into the contact elements located in the connectors when an inaccurate alignment exists between said contact elements and said plug contacts.

Moreover, it is known that in the conventional connections between the terminals attached to a printedcircuit board and the contact elements carried by a fixed connector, the curvature of the pluggable board entangles the connections, such as to cause a great increase in the power necessary to insert and remove the pluggable board from the connector or, in the worst case, to produce bad electrical contacts at the lpoints where the lack of alignment is greater. Furthermore, when the pluggable panel slides in guideways which are independent from the connector, inaccuracies of the connector mounting with respect to the guideways may produce the same difficulties even if the edge of the board bearing the plug contacts is perfectly smooth.

An analogous situation also occurs with boards of very large size. In this case, in order to reduce the board curvature, it is possible to use a plurality of connectors set side by side. Yet some possible misalignments of the different connectors may produce the aforementioned disadvantages.

These disadvantages are removed in the electrical con.- nector according to the invention, which provides an electrical edge connector for a printed-circuit board comprising a row of contact elements, each mounted in a cavity in an insulating receptacle and each comprising a wire bent into a closed form including two loops between which the edge of the board can be inserted, the two ends of the wire being anchored at a single point at the bottom of the cavity and the loops being so spaced from the walls of the cavity that the element as a whole can llex resiliently about the said point.

3,466,591 Patented Sept. 9, 1969 ICC Another problem, which is particularly important when one edge of the printed-circuit boards is provided with terminals of small size, is that of overcoming the effect of the inaccurate dimensions of said terminals in the longitudinal direction with respect to said edge.

In known systems a plug contact, inserted into a connector, may contact the contact element intended to receive the adjacent plug contact. Furthermore, even though the dimensional inaccuracy in the longitudinal direction may not be great, it often happens that the contact element of the connector which is not perfectly aligned with the corresponding plug contact cornes into contact with the insulating portion of the board, and consequently in this case a faulty electrical connection may result. The aforementioned inaccuracy of the dimensions is cumulatively due to the lack of precision of the printed circuit, to the inaccuracy of the connector and to theI lack of precision of the connector mounting especially in the case wherein a plurality of connectors assembled side by side are used for only one pluggable board.

The aforementioned difficulties are considerably reduced by means of the printed-circuit board according to the invention, comprising a series of terminals formed by portions of printed circuit and adapted to be plugged into a connector according to the invention, characterized in that said portions of the printed circuit lie in grooves of the board recessed with respect to the board surfaces, whereby said contact elements are guided towards said terminals by the projecting borders of said grooves.

These and other features of the invention will clearly appear from the following specification of a preferred embodiment thereof, by way of example and not in a limiting sense, with reference to the annexed drawings, wherein:-

FIG. 1 is a view of an assembly of electrical connectors for printed-circuit boards, according to the invention;

FIG. 2 is a sectional view taken along the line II-II in FIG. 1.

FIG. 3 is a sectional view taken along the line III- III in FIG. l.

Each connector 24, 25, 26 (FIG. l) comprises a receptacle 27 of an insulating material provided, for instance, with twenty cavities 28, each one containing a contact element 29. Each contact element 29 is made of an electrically conducting wire, bent into two loops as shown in FIG. l, and lying in a plane which is perpendicular to the major dimension of the connector. Both ends of the contact element 29 pass through a hole 30 in the base of the receptacle 27 and are firmly anchored to said receptacle by means of a plastic poured into the recess 31 of the base of the receptacle 27. The end 32 of the contact element 29 represents the free terminal of the contact element and protrudes from the base of the receptacle 27.

The plug contacts for the connectors 24, 25, 26 and 38 (FIGS. l and 2) are represented by tongues 33 of the circuit printed on each pluggable board 12, 13, 14.

As mentioned before, in known connectors employing bent wire contact elements, the ends of the contact eleL ment 29 are fixed to the receptacle 27 at points which are close to the external borders 34, 3S of the cavity 28. On the contrary, in the connector according to the invention, the contact element 29 when standing free takes a position which is considerably spaced from the borders 34 3S, of the cavity 28. Accordingly the two loops 36, 37 of the contact element 29 are enabled not only to diverge for receiving the terminal 33, but also may be displaced in the receptacle 27 towards the wall 34 or the wall 35 by resilient flexure around the anchorage -point (hole 30) within the receptacle, so as to adapt itself to the condition existing when the axis of the contact element 29 and the axis of the terminal 33 are misaligned. Therefore the connector according to the invention is adapted to permit the insertion of plug contacts, which are the terminals borne by a pluggable board, into the contact elements located in the connector, even when there is not an accurate alignment between said contact elements and said terminals.

In order to interconnect the printed circuits of different pluggable boards 12, 13, 14, connecting panels 20, 21 of insulating material are provided, bearing on their sides 22, 23 respectively printed circuits which can be connected to the circuits printed on the pluggable boards 12, 13, 14 through the terminals 32 of the connectors 24, 25, 26 respectively.

The end 32 of contact element 29 extends through the holes 47, 48 of the connecting panels 20, 21, and is interconnected, for instance by means of welding, with the circuit printed on the connecting panels. Therefore it is apparent that in the connector according to the invention a single series of terminals 32 serves as both the' electrical connection and the mechanical joint between the connector and the associated circuits.

In the case wherein, as seen in FIG. 2, a plurality of connectors 24, 38, are assembled side by side, for use with only one pluggable board 12, in order to compensate misalignment between the contact elements 29 and the terminals 33, the portions of the printed circuit which form said terminals 33 lie in grooves of board 12 as seen in FIG. 3 which are recessed with respect to the board surfaces, whereby said contact elements are guided towards said terminals by the borders of said grooves.

Alternatively said terminals 33 printed on said board 12 are separated by light projecting parts 39 comprising a varnish laid on said surfaces. In both cases, the contact elements, being made of a Wire having a circular section are quite liexible in a transverse direction with respect to their plane, and are guided by said projecting borders in such a way as to come correctly into contact with the corresponding terminals of said pluggable board, even in the case where a considerable misalignment exists between said contact elements and said terminals of said pluggable board.

Both portions of each terminal 33 printed on the two sides of the pluggable board are interconnected by solder 40 passing through the board.

Furthermore, the side walls 49 of each receptacle are adapted to enter the notches 41 of each pluggable board in order to facilitate the alignment of said connectors with respect to said board.

A suitable frame 45 supports the connecting panels 20, 21 with the associated connectors, and is provided with guideways 46 adapted to support and guide the pluggable boards during the inserting and the extracting operations.

It is understood that many changes, addition of parts and improvements may be made to the above described electrical connector without departing from the scope thereof.

What I claim is:

1. A printed-circuit board connecting assembly comprising:

(a) a board of insulating material having a plurality of parallel grooves extending perpendicularly from a border thereof, each of said grooves having a substantially flat bottom,

(b) conductive material on the bottom of said grooves and extending substantially the full width of said bottom, the surface of said conductive material being below the surface of said board and,

(c) an electrical connector comprising:

(l) a receptacle of insulating material having a plurality of cavities,

(2) a series of contact elements,.one in each of said cavities, each of said elements being formed of a single length of wire bent to form a pair of opposed coacting loops for receiving and engaging said board along one of said grooves for making electrical contact with the conducting material at the bottom thereof, the ends of said wire being ixedly anchored at a single point with said loops being spaced from the walls of said cavity for allowing resilient iiexure of said loops about said anchorage point.

References Cited UNITED STATES PATENTS 2,699,534 1/1955 Klostermann 339-193 3,082,395 3/1963 Madansky 339-17 3,157,452 1l/1964 Dorjee et al. 339-176 FOREIGN PATENTS 840,503 7/ 1960 Great Britain. 1,331,816 5/1963 France. 1,089,838 9/1960 Germany.

26,795 1/ 1964 Germany.

MARVIN A. CHAMPION, Primary Examiner P. A. CLIFFORD, Assistant Examiner U.S. Cl. X.R. 

